Curable optical adhesive composition

Abstract

The problem to be solved is to provide a curable optical adhesive composition in which the cured product has high hardness with excellent temperature stability and excellent elongation, and can accurately maintain the position of in-vehicle optical components under the temperature and motion conditions in which automobiles are operated. The solution of the problem is a curable optical adhesive composition comprising a curable optical resin composition comprising a (meth)acryloyloxy group-containing (meth)acrylic polymer (A), a high glass transition temperature vinyl-based monomer (B), a hard filler (C) and a polymerization initiator (D), wherein a cured product of the curable optical resin composition is an optical resin having a glass transition temperature of 125°C or higher and an elongation rate at room temperature of 3% or more.

Description

CURABLE OPTICAL ADHESIVE COMPOSITION

[0001] The present invention relates to a curable optical adhesive composition, and particularly to a curable optical adhesive composition for bonding in-vehicle optical components.

[0002] Patent Document 1 describes an epoxy-based dual-curable adhesive composition useful for bonding optical components of camera modules mounted on automobiles and smartphones. The dual-curable adhesive composition of Patent Document 1 includes a tetrakis (pentafluorophenyl)borate compound as the thermal cationic polymerization initiator instead of the conventional antimony-containing compound, and thus becomes an adhesive composition that has low toxicity, is able to be cured at a low temperature, and has high heat resistance of a cured product.

[0003] On the other hand, there has been an increasing demand for mounting large optical modules on automobiles in recent years. For example, LiDAR is a technique of irradiating laser light and measuring a distance to an object and a shape thereof based on information of reflected light. An in-vehicle LiDAR is a system that detects and measures a surrounding situation with high accuracy while a vehicle is traveling, and requires a camera module larger in size and higher in performance than smartphones.

[0004] When the optical module to be mounted on a vehicle increases in size, components also increase in size and weight, and a load applied to each component due to vibration during automobile operation also increases. The curable optical adhesive composition is formulated so as to increase the mechanical strength and hardness of the cured product in order to accurately maintain the installation position of the optical component over a wide range of operating temperatures of automobiles from below the freezing point to approximately 100°C. However, such a formulation means that the cured product is poor in flexibility, and is problematic in that the component is easily damaged when it is subjected to a large load within a short time due to vibration.

[0005] Patent Document 2 describes a method for curing a photocurable rubber composition. The photocurable rubber composition is a composition comprising a (meth)acryloyloxy group-containing (meth)acrylic polymer having a predetermined chemical structure and a photoradical polymerization initiator. The method for curing this is to irradiate it with a UV-LED lamp. In the composition, monomers having a radical polymerizable group such as a (meth)acrylic group can be used in combination for the purpose of improving physical properties of a cured product.

[0006] Patent Document 2 lists members in a wide range of industrial fields as applications of the cured product of the composition, and these are directed to members that have rubber characteristics and elasticity, such as sealing, impact absorption, impact, pressure dispersion, damping, sound absorption, soundproofing, and improvement of feeling of a contact portion with a human body.Prior art documents

[0007] Patent Documents Patent Document 1: Japanese Patent Laid-open Publication No. 2021-147584 Patent Document 2: Japanese Patent Laid-open Publication No. 2020-147616Summary of the invention

[0008] Problem to be solved by the invention The present invention solves the above-described problems, and an object of the present invention is to provide a curable optical adhesive composition in which a cured product exhibits high hardness with excellent temperature stability and excellent elongation, and can accurately maintain a position of an in-vehicle optical components under a temperature condition and a motion condition in which an automobile is operated.Solutions to the problems

[0009] The present invention provides the following aspects. <1> A curable optical adhesive composition comprising a curable optical resin composition comprising a (meth)acryloyloxy group-containing (meth)acrylic polymer (A), a high glass transition temperature vinyl-based monomer (B), a hard filler (C), and a polymerization initiator (D), wherein a cured product of the curable optical resin composition is an optical resin having a glass transition temperature of 125°C or higher and an elongation rate at room temperature of 3% or more.

[0010] <2> The curable optical adhesive composition according to aspect 1, wherein the monomer (B) has a glass transition temperature from 80 to 260°C, preferably from 100 to 250°C, more preferably from 120 to 250°C.

[0011] <3> The curable optical adhesive composition according to aspect 1 or 2, wherein the hard filler (C) has a linear expansion coefficient of 20 ppm / °C or less, preferably 12 ppm / °C or less, more preferably 10 ppm / °C or less.

[0012] <4> The curable optical adhesive composition according to any one of aspects 1 to 3, wherein a mass ratio of the polymer (A) to the monomer (B), that is A / B, is from 0.3 to 3, preferably from 0.5 to 2, more preferably from 0.6 to 1.5, and still more preferably from 0.8 to 1.25.

[0013] <5> The curable optical adhesive composition according to any one of aspects 1 to 4, wherein a mass ratio of hard filler (C) to total resin (A+B), that is (C / (A+B)), is from 1 to 3, preferably from 1.2 to 2.5 and more preferably from 1.5 to 2.

[0014] <6> The curable optical adhesive composition according to any one of aspects 1 to 5, wherein the polymerization initiator (D) comprises a photoradical polymerization initiator (D1) and a thermal radical polymerization initiator (D2).

[0015] <7> The curable optical adhesive composition according to any one of aspects 1 to 6, wherein the polymer (A) has a number average molecular weight from 3,000 to 100,000, preferably from 10,000 to 90,000, more preferably from 30,000 to 80,000.

[0016] <8> The curable optical adhesive composition according to any one of aspects 1 to 7, wherein the monomer (B) comprises at least one selected from the group consisting of isobornyl acrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and combinations thereof.Effects of the invention

[0017] The present invention provides a curable optical adhesive composition in which a cured product exhibits high hardness with excellent temperature stability and excellent elongation, and can accurately maintain a position of an in-vehicle optical component under a temperature condition and a motion condition in which an automobile is operated. As the in-vehicle optical component, a component of a large in-vehicle optical module such as an in-vehicle camera for LiDAR is able to be exemplified.Detailed description

[0018] Hereinafter, one embodiment of the present invention will be described in detail, but the scope of the present invention is not limited to one embodiment described herein, and various modifications can be made without departing from the gist of the present invention. In addition, when a plurality of upper limit values and lower limit values are described for a specific parameter, an arbitrary upper limit value and an arbitrary lower limit value among these upper limit values and lower limit values are able to be combined to obtain a suitable numerical range.

[0019] 1. Curable optical resin composition The curable optical adhesive composition of the present invention comprises a curable optical resin composition comprising the following ingredients (A) to (D).

[0020] <(A) (Meth)acryloyloxy group-containing (meth)acrylic polymer> The curable optical resin composition includes a (meth)acryloyloxy group-containing (meth)acrylic polymer, whereby it is possible to provide a cured product of a curable optical adhesive composition (hereinafter, may be simply referred to as a "cured product") having sufficient flexibility to absorb a load when the load applied to an in-vehicle optical component is increased.

[0021] As the (meth)acryloyloxy group-containing (meth)acrylic polymer, a polymer having the main chain being a (meth)acrylic acid ester polymer and having a (meth)acryloyloxy group can be used. Such a polymer is preferably produced by anionic polymerization or radical polymerization, and radical polymerization is more preferable from the viewpoint of versatility of the monomer or ease of control. Among radical polymerizations, living radical polymerization or radical polymerization using a chain transfer agent is preferable, living radical polymerization method is more preferable, and atom transfer radical polymerization method is particularly preferable. When a living radical polymerization method is used, a polymer having a (meth)acryloyloxy group at the polymer chain terminal can be obtained.

[0022] The (meth)acryloyloxy group-containing (meth)acrylic polymer (A) has a number average molecular weight from 3,000 to 100,000, preferably from 10,000 to 90,000 and more preferably from 30,000 to 80,000. When the molecular weight is too low, the flexibility of the cured product is impaired, and the elongation tends to decrease. On the other hand, when the molecular weight is too high, the viscosity of the curable optical adhesive composition tends to be high, and the curable optical adhesive composition tends to be difficult to handle.

[0023] Examples of the (meth)acryloyloxy group-containing (meth)acrylic polymer include poly(n-butyl acrylate / ethyl acrylate / methoxyethyl acrylate) having acryloyl groups at both terminals described in Synthesis Example 1, poly(n-butyl acrylate / 2-ethylhexyl acrylate) having acryloyl groups at both terminals described in Synthesis Example 2, and poly(n-butyl acrylate) having acryloyl groups at both terminals described in Synthesis Example 3 in Patent Document 2; methacryloyl group-terminated poly(n-butyl acrylate) described in Example 3, methacryloyl group-terminated poly(n-butyl acrylate) described in Example 6 in Japanese Patent Laid-open Publication No. 2000-72816; n-butyl polyacrylate having acryloyl groups at both terminals described in Production Example 1, n-butyl polyacrylate having a acryloyl group at one terminal described in Production Example 2 in WO2012 / 008127; poly(n-butyl acrylate / ethyl acrylate / 2-methoxyethyl acrylate) having acryloyl groups at both terminals described in Production Example 1 in WO2005 / 000927; poly(n-butyl acrylate / 2-ethylhexyl acrylate) having acryloyl groups at both terminals described in Production Example 2 and poly(2-ethylhexyl acrylate) having acryloyl groups at both terminals described in Production Example 3 in WO2006 / 112420.

[0024] As a backbone of the (meth)acryloyloxy group-containing (meth)acrylic polymer, many polymers such as polymethyl methacrylate (MMA), polystyrene (St), poly(acrylonitrile (AN) / St), poly(2-hydroxyethyl methacrylate (HEMA) / MMA) and poly(HEMA / butyl methacrylate (BMA)) are commercially available.

[0025] Examples of commercially available products of the (meth)acryloyloxy group-containing (meth)acrylic polymer include macromonomers AA-6, AA-714, AB-6, AJ-7, AN-6, AS-6, AW-6, AZ-8, HA-6, HN-6 and HS-6 manufactured by Toagosei Co., Ltd., XMAP RC-100C, RC-200C, and RC-300C manufactured by KANEKA CORPORATION (all trade names).

[0026] <(B) High glass transition temperature vinyl-based monomer> The curable optical resin composition includes a high glass transition temperature (Tg) vinyl-based monomer, thereby allowing provision of a cured product in which the hardness is highly maintained over the operating temperature of an automobile.

[0027] As the high Tg vinyl-based monomer, for example, a vinyl-based monomer having a Tg from 80 to 260°C, preferably from 100 to 250°C and more preferably from 120 to 250°C can be used. The Tg of the high-Tg vinyl-based monomer indicates the Tg of its homopolymer. As the Tg exhibited by a homopolymer of a monomer, a generally known value is adopted (for example, "Collection of Case Examples of Selecting Functional Monomers", Technical Information Society 2017, Macromolecules 1996, 29, 8954-8959).

[0028] Specific examples of the high-Tg vinyl-based monomer are shown below.

[0029]

[0030] Among these, it is preferable to use a high Tg vinyl-based monomer such as isobornyl acrylate, isobornyl methacrylate, or 3,3,5-trimethylcyclohexyl methacrylate, and isobornyl acrylate and isobornyl methacrylate are particularly preferable.

[0031] <(C) Hard filler> The curable optical resin composition includes a hard filler. Using the hard filler can control the linear expansion coefficient of the cured product of the curable optical resin composition. Particles of a material having a linear expansion coefficient of the hard filler of 20 ppm / °C or less, preferably 12 ppm / °C or less and more preferably 10 ppm / °C or less are used.

[0032] A preferable hard filler is a transparent inorganic filler. Specific examples of the transparent inorganic filler include silica fillers such as colloidal silica, hydrophobic silica, fine silica and nanosilica, silica beads, glass beads, and alumina beads.

[0033] The average particle size (if not granular, its average maximum size) of the hard filler is not particularly limited, and is preferably 0.01 μm or more from the viewpoint that the curable optical adhesive composition is excellent in handling. The average particle size (if not granular, its average maximum size) of the hard filler is preferably 50 μm or less, from the viewpoint that the hard filler is dispersed uniformly in the curable optical adhesive composition. The average particle size of the hard filler is preferably from 0.1 to 30 μm and more preferably from 1 to 20 μm. In the present invention, the average particle size of the hard filler is measured by a Nanotrac dynamic light scattering particle size analyzer.

[0034] Examples of commercially available products of the hard filler include glass beads (product name "EGB210C" (average particle size 18 μm), manufactured by Potters-Ballotini Co., Ltd.), high purity synthetic spherical silica (product name "SO-E5" (average particle size 2 μm), product name "SO-E2" (average particle size 0.6 μm), manufactured by ADMATECHS Co., Ltd.), silica (product name "FB7SDX" (average particle size 10 μm), manufactured by Tatsumori Co., Ltd.) and silica (product name "TS-10-034P" (average particle size 20 μm), manufactured by Micron Co., Ltd.). Only one type of the hard filler may be used, or two or more types thereof may be used in combination.

[0035] <Blending amount of ingredients A, B, and C> In the curable optical resin composition, the mass ratio A / B of the polymer (A) to the monomer (B) is from 0.3 to 3. When the mass ratio is less than 0.3, flexibility for absorbing a load applied to the in-vehicle optical component may be insufficient. When the mass ratio exceeds 3, the hardness of the cured product may be insufficient at the operating temperature of the automobile. The mass ratio is preferably from 0.5 to 2, more preferably from 0.6 to 1.5 and still more preferably from 0.8 to 1.25.

[0036] In the curable optical resin composition, the mass ratio C / (A+B) of the hard filler (C) to the total of all resin ingredients, that is, the total of polymer (A) and the monomer (B) is from 1 to 3. When the mass ratio is less than 1, the linear expansion coefficient of the cured product may not follow the thermal expansion behavior of the bonded optical component. When the mass ratio exceeds 3, the viscosity of the adhesive agent is too high, and the coatability may be impaired. The mass ratio is preferably from 1.2 to 2.5 and more preferably from 1.5 to 2.

[0037] <(D) Polymerization Initiator> The curable optical resin composition includes a photoradical polymerization initiator (D1). Using the photoradical polymerization initiator (D1) allows easy curing under a temperature environment from room temperature to a slightly higher temperature. The curable optical resin composition preferably includes a thermal radical polymerization initiator (D2). Sufficiently curing the curable optical resin composition in a high-temperature environment using a thermal radical polymerization initiator allows the hardness of the cured product of the curable optical resin composition to be improved.

[0038] Examples of the photoradical polymerization initiator include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 1-hydroxycyclohexyl-phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4'-diphenylbenzophenone and 4,4'-diphenoxybenzophenone. Among these, 2-hydroxy-2-methyl-1-phenyl-propane-1-one is preferably used.

[0039] The content of the photoradical polymerization initiator can be appropriately selected according to the light irradiation amount and the additional heating temperature.

[0040] Examples of the thermal radical polymerization initiator include azobisisobutylnitrile, benzoyl peroxide, tert-butyl peroxypivalate, tert-butyl peroxineohexanoate, tert-hexylperoxineohexanoate, tert-butyl peroxineodecanoate, tert-hexylperoxineodecanoate, cumyl peroxineohexanoate, cumyl peroxineodecanoate and 1,1,3,3,-tetramethylbutylperoxy-2-ethylhexanoate. Among these, 1,1,3,3,-tetramethylbutylperoxy-2-ethylhexanoate is preferably used.

[0041] The content of the thermal radical polymerization initiator can be appropriately selected according to the heating temperature, the oxygen abundance during radical polymerization.

[0042] <Properties of cured product> The cured product of the curable optical resin composition has a Tg of 125°C or higher. The Tg of the cured product of the curable optical resin composition is a value determined from a peak value of a loss tangent measured using a dynamic viscoelasticity measuring instrument.

[0043] When the Tg of the cured product is less than 125°C, the cured product of the curable optical adhesive composition is likely to be softened when the automobile has a high temperature, and the position of the in-vehicle optical component is likely to be shifted. The cured product has the problem of becoming brittle when the Tg becomes too high. In general, the upper limit of Tg of the cured product is 200°C or less. In addition, the range of the Tg of the cured product is, for example, from 125 to 200°C, preferably from 140 to 190°C and more preferably from 150 to 180°C.

[0044] The cured product of the curable optical resin composition has an elongation rate of 3% or more at room temperature. The elongation rate of the curable optical resin composition is an elongation rate at break measured with a sample and a method in accordance with JISK6251.

[0045] When the elongation rate of the cured product at room temperature is less than 3%, the cured product of the curable optical adhesive composition is brittle, and is easily damaged when a large load is applied to an optical component in a short time due to vibration of an automobile. The cured product has the problem of being easily deformed as the elongation rate increases. In general, the upper limit of the elongation rate of the cured product is 100% or less. The elongation rate of the cured product is preferably 5% or more and more preferably 7% or more. The range of the elongation rate of the cured product is, for example, from 3 to 100%, preferably from 5 to 80%, more preferably from 7 to 73% and still more preferably from 10 to 61%.

[0046] 2. Optional ingredient The curable optical adhesive composition of the present invention may include the following ingredients in addition to the ingredients of the curable optical resin composition.

[0047] <Polyfunctional monomer> The curable optical adhesive composition may include a polyfunctional monomer. Using the polyfunctional monomer allows the tensile strength of the cured product to be further improved.

[0048] The polyfunctional monomer refers to a monomer having three or more polymerizable carbon-carbon double bonds in the molecule. The polymerizable carbon-carbon double bond includes a vinyl group, an allyl group, a (meth)acrylic group, and a (meth)acryloyl group.

[0049] Specific examples of the polyfunctional monomer include trimethylolpropane triacrylate, neopentyl glycol polypropoxy diacrylate, neopentyl glycol diacrylate, trimethylolpropane polyethoxy triacrylate, bisphenol F polyethoxy diacrylate, bisphenol A polyethoxy diacrylate and dipentaerythritol polyhexanolide hexacrylate. Among these, polyfunctional monomers such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate are preferably used, and trimethylolpropane triacrylate is particularly preferably used.

[0050] When the curable optical adhesive composition includes a polyfunctional monomer, the content thereof is not particularly limited, and is, for example, from 0 to 5 mass%, preferably from 0 to 3 mass%, and more preferably from 0 to 2 mass% based on the entire curable optical adhesive composition.

[0051] <Thixotropy imparting agent> The curable optical adhesive composition may include a thixotropy imparting agent such as fumed silica. When the thixotropy imparting agent is used, stringing and spreading can be suppressed during application of the curable optical adhesive composition. In addition, the fumed silica also functions as an inorganic filler, and using the fumed silica allows the tensile strength of the cured product to be further improved. Examples of commercially available products of fumed silica include: product name "HDK H2000", manufactured by Asahi Kasei Wacker Silicone Corporation; product name "Cab-O-Sil TS-720", "TS-530", manufactured by Cabot Corporation; and product name "AEROSIL R 974", manufactured by Nippon Aerosil Co., Ltd.

[0052] When the curable optical adhesive composition includes fumed silica, the content thereof is not particularly limited, and is, for example, preferably from 0.5 to 10 mass%, more preferably from 1 to 7 mass% and more preferably from 2 to 5 mass% based on the entire curable optical adhesive composition.

[0053] 3. Curable optical adhesive composition The curable optical adhesive composition of the present invention is a composition that is applied to an adherend and cured, and includes the curable optical resin composition described above and, if necessary, the additive ingredient described above.

[0054] <Manufacturing method> The curable optical adhesive composition may be prepared by any method as long as the curable optical resin composition and the above ingredients are able to be dispersed and mixed. As a general method, a curable optical adhesive composition is able to be obtained by weighing ingredients, mixing and kneading the ingredients using a scraper, a mixing roll (such as a three-roll mill), a planetary mixer, or the like, and defoaming the mixture if necessary.

[0055] <Curing method> The method for curing the curable optical adhesive composition of the present invention preferably includes a photocuring step of curing the composition by light irradiation and a thermal curing step of further post-curing the composition by heating. The curable optical resin composition is cured by light irradiation and further subjected to a heat treatment, whereby the curable optical adhesive composition is sufficiently cured, and the hardness of the cured product is improved.

[0056] In the photocuring step, the light to be irradiated preferably includes light in a wavelength range from 300 nm to 500 nm, and more preferably includes ultraviolet light having a wavelength of 400 nm or less (preferably from 350 to 380 nm). The light source is not particularly limited, and examples thereof include an ultraviolet LED, a blue LED, a white LED, a laser, a metal halide lamp, a xenon lamp, and a high-pressure or intermediate-pressure mercury lamp. The irradiation amount of light is not particularly limited, and the intensity at a wavelength of 365 nm is preferably from approximately 10 to 1000 mW / cm2and more preferably from approximately 100 to 800 mW / cm2. The light irradiation time is not particularly limited, and is, for example, 2 seconds to 5 minutes.

[0057] In the thermal curing step, the heating temperature is preferably from 60°C to 150°C, more preferably from 80°C to 125°C. The heating time is not particularly limited, and is preferably, for example, from 10 minutes to 4 hours.

[0058] <Application> The curable optical adhesive composition of the present invention is able to be used in various fields. In the optical equipment field, the curable optical adhesive composition can be used as an adhesive agent for a camera module, a LiDAR module (light detection and ranging, detection and ranging by light (including laser and infrared rays)), a lens material of a steel camera, a finder prism, a target prism, a finder cover, a light receiving sensor unit, a photographing lens and a projection lens of a projection television. Examples of bonding places of the camera module include a space between an image sensor (imaging element) such as a CMOS or a CCD and the substrate, a space between the cut filter and the substrate, a space between the substrate and the housing, a space between the housing and the cut filter and a space between the housing and the lens unit. In other fields, in the fields of automobiles and transportation equipment, the curable optical adhesive composition can be used, for example, adhesion of switch parts for automobiles and electrical components; in a flat panel display, sealing or adhesion of a liquid crystal display, organic electroluminescence, a light emitting diode display device and a field emission display, and an ink material; in the recording field, adhesion of video discs, CDs, DVDs, MDs, pickup lenses, peripherals of hard discs (spindle motor member, magnetic head actuator member), and Blu-ray discs; in the field of electronic materials, structural bonding and coating of electronic components; and in the field of optical components, sealing and bonding around an optical switch, an optical fiber material around an optical connector, an optical passive component, an optical circuit component, an optoelectronic integrated circuit, in an optical communication system.

[0059] Examples of the adherend to which the curable optical adhesive composition of the present invention is able to be used include glass, various metals, porous members and films and plates of resins. Examples of the various metals include aluminum, nickel, iron, and stainless steel. Examples of the porous member include ceramics. Examples of the resins as a raw material of the film and the plate of the resin include polycarbonate, PPS, PBT, PA, LCP, FR4, and FR5.

[0060] As a preferable aspect, the curable optical adhesive composition of the present invention is used for assembly of a camera module. More specifically, the curable optical adhesive composition of the present invention is preferably used for bonding a lens holder and a substrate on which an imaging element is fixed in camera module assembly. In the above description, the camera module is not particularly limited, and is, for example, a small camera module used for a smartphone or an in-vehicle camera.Examples

[0061] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0062] First, the following materials were prepared as raw materials.

[0063]

[0064] <Preparation of curable optical adhesive composition> The materials in Table 2 were blended in the proportions shown in Table 4, and kneaded and dispersed using a planetary mixer to prepare curable optical adhesive compositions of Examples and Comparative Examples. Each of the obtained curable optical adhesive compositions was evaluated as follows. The results are shown in Table 4.

[0065] <Elongation rate at break> The curable optical adhesive composition was applied onto a release film, irradiated with 365 nm-UV-LED (500 mW / cm2) for 5 seconds, and then cured at 120°C for 60 minutes using a hot air circulating oven to prepare a JIS Z1702 No. 3 dumbbell test piece (thickness: 1 mm). The dumbbell test piece was placed on "Autograph 5900R" (trade name) manufactured by Instron Corporation, pulled at a speed of 10 mm / min at room temperature, and the elongation rate when the test piece was broken was recorded.

[0066] <Glass transition temperature (Tg)> The curable optical adhesive composition was applied onto a release film, irradiated with 365 nm-UV-LED (500 mW / cm2) for 5 seconds, and then cured at 120°C for 60 minutes using a hot air circulating oven to prepare a test piece having a thickness of 1 mm. The test piece was placed in a dynamic viscoelasticity measuring instrument 6100 manufactured by SII NanoTechnology Inc., and the Tg was determined from the peak value of the loss tangent measured under the following conditions.

[0067]

[0068]

Claims

1. A curable optical adhesive composition comprising a curable optical resin composition comprising a (meth)acryloyloxy group-containing (meth)acrylic polymer (A), a high glass transition temperature vinyl-based monomer (B), a hard filler (C) and a polymerization initiator (D), wherein a cured product of the curable optical resin composition is an optical resin having a glass transition temperature of 125°C or higher and an elongation rate at room temperature of 3% or more.

2. The curable optical adhesive composition according to claim 1, wherein the monomer (B) has a glass transition temperature of from 80 to 260°C.

3. The curable optical adhesive composition according to claim 1, wherein the hard filler (C) has a linear expansion coefficient of 20 ppm / °C or less.

4. The curable optical adhesive composition according to claim 1, wherein a mass ratio of the polymer (A) to the monomer (B), that is A / B, is from 0.3 to 3.

5. The curable optical adhesive composition according to claim 1, wherein a mass ratio of the hard filler (C) to total resin (A+B), that is C / (A+B), is from 1 to 3.

6. The curable optical adhesive composition according to claim 1, wherein the polymerization initiator (D) comprises a photoradical polymerization initiator (D1) and a thermal radical polymerization initiator (D2).

7. The curable optical adhesive composition according to claim 1, wherein the polymer (A) has a number average molecular weight from 3,000 to 100,000.

8. The curable optical adhesive composition according to claim 1, wherein the monomer (B) comprises at least one selected from the group consisting of isobornyl acrylate, isobornyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and combinations thereof.

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